The present invention relates to a disk array device and a control method of the disk array device.
An information processing apparatus performs every type of processing by inputting and outputting data to and from magnetic disks. However, the performance of accessibility to magnetic disks stays much lower than the access performance relative to semiconductor memory devices. In view of this, a cache memory with a semiconductor memory as its storage element is provided within a disk control device, for temporarily storing data of a magnetic disk(s) in the cache memory to thereby enhance the performance of access from the information processing apparatus.
As the performance of accessing to this cache memory significantly affects the processing performance in the information processing apparatus, several schemes have been employed for expanding the bus width of the cache memory within the disk control device and/or for accelerating bus clocks to thereby further enhance the access performance to the cache memory. Additionally in JP-A-2000-250712, there is disclosed a method for providing a data transfer integrated circuit (selector) and for selecting, when contention or conflict occurs between access requests to a cache memory, a certain number of ones from among the access requests, which number corresponds to the number of data buses coupled to the cache memory.
Unfortunately, since there is a limitation of the space in the substrate which can be utilized for the disk array device, it is difficult to expand the bus width of cache memory.